The present disclosure relates to a display device including a self-luminous light emitting element which includes an organic layer, and a method of manufacturing the same.
In recent years, as a display device in substitution for a liquid crystal display, an organic EL display device using a self-luminous organic EL (electro luminescence) element which includes an organic layer has been put into practical use. Since the organic EL display device is self-luminous, the organic EL display device has a wide viewing angle in comparison with liquid crystal or the like. Further, the organic EL display device has sufficient response characteristics to a high-definition and high-speed video signal.
In driving methods of the organic EL display device, an active matrix method in which a thin film transistor (TFT) is used as a drive element is superior in terms of response characteristics and resolution, in comparison with a passive matrix method. Thus, the active matrix method is regarded as an especially-appropriate drive method in the organic EL display device having the above-described features. The organic EL display device employing the active matrix method includes a drive panel in which an organic EL element including an organic light emitting layer, and a drive element (the above-described thin film transistor) for driving the organic EL element are disposed. Further, the drive panel and a sealing panel are bonded to each other by an adhesive layer so as to sandwich the organic EL element in between. The organic EL element has a structure in which the organic light emitting layer is formed between a pair of electrodes.
The organic EL display device is classified into a bottom emission method type in which light from each organic EL element is emitted to the drive panel side, and a top emission method type in which the light is emitted to the sealing panel side in reverse. In the case where the both methods are compared, the top emission method is advantageous in that the aperture ratio may be further improved.
Here, in the organic EL display device employing the top emission method, an electrode on light extraction side, that is, an electrode on the sealing panel side is an electrode used in common to each of the organic EL elements, and is, for example, composed of a light transmissive conductive material such as ITO (indium tin oxide). However, in such a light transmissive conductive material, the resistance is approximately double-digit or triple-digit higher in comparison with a typical metal material. Thus, since a voltage applied to the electrode on the light extraction side becomes non-uniform in the plane, the variation of the light emission luminance depending on the position is generated among each of the organic EL elements, and there is an issue that the display quality is lowered.
As a display device to solve this issue, for example, there is known organic EL display devices disclosed in Japanese Unexamined Patent Publication Nos. 2004-207217, and 2005-11810. In those organic EL display devices, an auxiliary wiring connected to an electrode (upper electrode) on the light extraction side which is on the same layer level as an electrode (lower electrode) on the drive panel side is formed, and a voltage drop is suppressed in the in-plane direction of the lower electrode.